Bi-polaron Transport and Magnetic Field Induced Pauli Spin Blockade in Redox-Active Molecular Junctions

We report the bi-polaron transport and magnetic field induced Pauli spin-blockade in solid-state molecular junctions (MJs) evidenced by a positive magnetoresistance (MR). The junction was made of thin layers of redox-active ruthenium polypyridyl-oligomers Ru(tpy)(2) sandwiched between conducting amorphous carbon (a-C) electrodes. The redox-active Ru(tpy)(2) molecule, which enables small polaron and deep traps in the charge transport of the Ru(tpy)(2) MJ as revealed by the temperature-dependent current-voltage response, leads to the formation of the bi-polaron and magnetic field induced Pauli spin blockade, resulting into the MR. At the meantime, the reliable and controllable device performance renders a rigid thickness-dependent MR evolution. The bi-polaron transport revealed in our study underscores the importance of the multi-particle transport by molecular design in MJs and laid the foundation for magnetic-electronic function in molecular-scale devices.

Automated summary

In this study, we report the transport of bi-polarons and the magnetic field induced Pauli spin-blockade in solid-state molecular junctions (MJs) through the observation of positive magnetoresistance (MR). The introduction of redox-active Ru(tpy)(2) molecules leads to the formation of bi-polarons and the magnetic field induced Pauli spin-blockade, resulting in the observed positive MR. Additionally, the reliable and controllable performance of the devices allows for a rigid thickness-dependent MR evolution.